Conversion of hydrocarbons



Aug i0, W43., c; W, wATsoN CONVERSION oF HYDRocARBoNs Filed May 24; 1941N Iv w 5 T. R Y Y Q. m3 WH m M W N \Luu-.:n 5 m. N l Uo/T U 4. A a

M, wmv JM Nm w Inv E um@ Nw r w mlm J N among, :Je \\.mm

Ow mi crude in a heated condition directly from the topping or reducingstills and a line 2l is indicated for so introducing the hot residue.

The tarry condensate obtanedrin'thedephlegmating section I3 from theprimary dephlegmation of the vapors from the coking drum B may bewithdrawn as a liquid fuel product condensate and unvaporized residuewithdrawn through line 22 and passed through a branch line 25 into theline 23. rlhe pump 24 directs the oil, as withdrawn either from sectioni3 or from trapout tray IB, through a line 26 to a heating coil 21disposed in a furnace 28 and the heated products pass through a transferline 29 to the reaction chamber A.

In some cases the heating of the heavy oil in the coil 21 may be omittedand the oil by-passed through a line 30 directly to the transfer line 29thence to the reaction chamber A.

Vapors uncondensed in the tower C pass through a line 3l to thefractionator D wherein lin the' coil' I8 and the heated residuumintroduced into the tower C. Constituents of the nature of kerosene andgas oil are distilled off the residue in the tower C and passed to thetower D tothe vapors are fractionated to separate higher boilingrefluxcondensate from lighter vapors and gases. `'Ihe reux condensate iswithdrawn by a pump 32 and directed through a line 33 to a heating coil34 disposed in a furnace y35 and the heated products are passed througha transfer line 3G to the reaction chamber A or to the transfer line 29so as to combine the heated products with the heavy oil stock beingdelivered from the heating coil 21 or from the by-pass line 30 AUncondensed vapors from the tower D pass to a condenser 31 and thedistillate is collected in a receiving drum or gas separator 38.V Thedrum 38 is maintained under superatmospheric pressure and normallygaseous hydrocarbons, predominantly methane and C2 hydrocarbons, aswellas hydrogen, are removed through a gas line 33 while the gasoline ornaphtha distillate containing normally gaseous hydrocarbons.predominantly C3 and C4 hydrocarbons, is collected as a liquid in thedrum. The liquid distillate is withdrawn by a pump 40 and conductedthrough a line 4| to a rectifying tower 42 wherein the distillate issubjected to rectification. or stabilization to remove normally gaseoushydrocarbons and the rectified product is withdrawn through a line 43.The uncondensed gases passte a condenser 44 thence to a receiving drum45 having a gas outlet 45. The liquid distillate inthe drum 45comprising predominantly C3 and C4 hydrocarbons is withdrawn by a pump41 and directed through a line 48 to a heating coil 49disposed in afurnace 50. The heated products pass through a transfer line 5l to thereaction chamber orftransfer line 29 so that the heated products may becombined with the other products undergoing reaction in reaction chamberA. The normally gaseousjhydrocarbons being passed` through the coil 49may be subjected to temperature pressure conditions therein adequate toeffect polymerization into liquid hydrocarbons. In an alternativeoperation the normally gaseous hydrocarbons may be merely preheated incoil 49 and then directed through a branch line 52.1or combining withthe cycle condensate being passed through the heating coil 34 whereinthe mixture yof normally liquid and normally gaseous hydrocarbons issubjected drocarbons.

gether with cracked constituents from which tower the reflux condensateis cycled to the cracking or conversion coil 34. The gasoline distillateis collected in the receiver 33 and the gasoline is stabilized in thetower 42 under superatmospheric pressure. The overhead from the towerwhich collects in receiver 45 consists essentially of the heavier of thenormally gaseous hydrocarbons, more particularly C3 and C4 hy- A portionof the distillate collecting in the receiver 45 is normally employed forrefluxing the tower 42 and the remainder is directed to the coil 49wherein it is subjected to polymerizing temperatures such astemperatures of the order of 900 F. and 1000 F. under pressures of theorder of 500 to 1000 lbs. land the resultant products of conversion aredirected to the reaction chamber A for further reaction with the otherhydrocarbons therein. If it is not desired to subject the C304 fractionsto separate polymerization the coil 49 may be used as a preheating coiland the preheated normally gaseous hydrocarbons combined with the refluxcondensate passing from the tower D to the conversion coil 34. In someycases it is advantageous to subject the normally gaseous hydrocarbons inthe coil 49 to high temperatures of the order 'of 1000 to 1200 F. toeiiect an increase in the olein content thereof and combine theresultant products of conversion with the cyclecondensate in the coil34. In the coil 34 the mixture of normally liquid hydrocarbons andnormally gaseous hydrocarbons is subjected to temperatures of the orderof 900 F. or 1000 F. under pressures such as 400 to 800 lbs. to effectcracking and reversion reactions and to concomitantly effect conversionof higher boiling normally liquid hydrocarbons into lower boilingproducts and conversion of normally gaseous hydrocarbons into higherboiling hydrocarbons within the gasoline boiling range. The products ofconversion are combined with the black oil introduced directly from thetower C through line 30 or after heating in the coil 21 for furtherreaction in the reaction chamber A. d

It is advantageous to subject the topped or reduced crude to viscositybreaking in the coil i8 before introducing to the tower C. In such anYoperation the heating in the coil 21o-f the mixture of unvaporzedresiduum Vand reflux condensate which is drawn from the tower C maygenerally be omitted and the mixture may be cornbined directly with thehot products from the reversion coil 34 or with the hot products fromboth heating coils 34 and 49. When employing the coil 21 the black oilstock is subjected to cracking or viscosity breaking therein undertemperatures of the order of 800 F. or 900 li. and under pressures suchas 200 to 600 lbs.

The reaction chamber A should be maintained under pressures at leastasyhigh as about 200 lbs. and preferably under pressures of the order of300 to 600 lbs. It is desirable to maintain somewhat high pressures inthe tower A in order to promote continued reactions of the nature ofaseo-,iso

It is preferred to maintain in the reaction cham`V bei" A as high atemperature as is possible without cokrrg and this temperature willordinarily be in the neighborhmciof 900 *Et-930 F. Liquid is preventedfrom accumulating in the chamber A by the rapid Vwithdrawal of theliquid residue through the line- M; While a single down-flow reactionchamber has been ilhistrated it is to be' understood that the reactionzone in which the commi-'ngled products from the heating coils aresubjected to reaction may' assu-me various forms. For example, it isadvantageousto provide an initial downiiow reaction chamber with all ofthe products, both vapors and liquid, passing together withoutseparation into a subsequent upflow' reaction chamber fro-rnwhichvvapors are at the top and a mixture of vapors and liquid residuewithdrawn fromI the bottom for* passage to the eoking drum". Anotheradvantageous arrangement is to provi-de a counterflow` reaction chamberwith the black oil stream bei-ng introduced' to an upper portion and thestream from heater 342 being admittedl to a lower portion of thechamber.

The temperature required for colring depends on the pressure andcharacter ofthe stock introduced into) the ocking drum- In general atemperature in excess or 825i" is required: in order to eil'ectlcolti-ng tot" the production ol' a marketable cuire: and thetemperaturesused` will ordinarily* be about 840i F. to 85F Atemperatute, for example; of 860' E'. under pressures of 1154-! FZ lbs.in the coburg' drum is quite satisfactory; Tis-ie passage material.'trom the reaction mating the coking drum pressure A. .relatively smallamount' of cooling applied. to the de'- phlegmator it, as bytheirrtroduction. of a small amount o1 cycle condensate, in ordertoprevent cokmg in the dephl'egmator. When running to coke only thetemperature in the dephlegmator may be Vmaintained vwithout coking at asomewhat higher range than when ,drawing a fuel oil` productffzsom thedephlegrnator. Thus, for example,- in tlfxey coke onlygoperationtemperatures of around 810 il.` to 820 F. may be maintained inthedephlegm-ator and when running to coke and fuel oil temperatures ofabout '290 F. to 800 may be maintained.. When running to coke anddistillate hiel` oilthe mixture of. uniza-` porzcd residuum and reflux"condensate may be withdrawn from the tray I6 at tempera-turesapproximately 800 F. The top ot the tower C may A be maintained at.temperatures approximating chamber A through. the lino t0* to the`coking drum E is controlled so to. continuously' pass of the liquid;together with a. sumcient. portion of the` vapors to maititam thedesired aching temperature the coking without causing priming through.the vapor line or the. ooking drurm A relativelysnrallz ptomirdon of theval e required. for this: purpose. a proportion vapors leaving thereaction chamber. By operating inthis manner itfis possible to obtain?charging rates' and recycling ratos.: that is,. rates oi tor` the' cyclecondensate andV `recycle gases for the: black ol@, oit an extremely highmagnitude; which igtv has7 been impossibleito reach in priori methodsot, operation. For example; on equipment in which therlintit in' the gasoil Ife-v cycling ratelv was within. thzerange of 230v to 280 bbls. perhour order toavoid` priming, in the coliiog the prac-tice ot theirrnfentiorr maires may be obtained;

The iractionating towers C and D are advantageously maintained underpressures approximately' the orderV of 10% of` the; total 710 F. to'I300 F. under about 150 lbs` pressure andthe bottom of tower D may beheld. at temperatures around 66061, to 690 F;

Y In general the higher the pressure applied. in the coking drum thegreater will be the yield off coke and when running to coke anddistillate fuel. oil Athe higher the pressure vthe greater the ratio ofcoke to fuell oilr The pressure carried in the cokng drum mayaccordingly be varied somewhat. in accordance with the requirements forcolte` and fuel oil., It is desirable however. toY maintain sufficientpressure in the coking, drumf tru-'insure the proper separation inV thercoeivingdrum 3B. In other. words, in order to obtain the desiredretention of C3. and C); hydro#` carbons in` the distillate withdrawn`from the receiver 38' it is desirable that the pressure should he atleast as high. as 1.00 lbs. and preferably V1.50 lbs. or more. When thecoking opera.- ti'on is carried on under low pressure such as 50 lbs. itmay be desirable to subject. the gases passing through` the line 39 toadditional fractionation or absorption norder to :recoverV C3 and C4.hydrocarbons thereirorn. In an alternative method of. operation thetowers C and D are maintained under pressures approximating Vthepressure in the. reaction chamber A. and under measures of 200 lbs. orhigher which insuresl a very good separation in .the receiver 3S, whilethe coking drum is operated under desired low pressure such` as aroundlbsr and. the vapors from the coking. drum are separately corrdensedand.. the distillate reuxed on either or vboth of the..towers C and D.

While I. have described a particular embodiment of my invention forpurposes. of. illustra tioru. it shouldv be understood. that variousymodicatons and adaptatif;ns4 thereof which will be obvious to oneskiliedin the art, may be made within the spirit; of. theY invention. asset forth in the appended claimst 1.-. In the conversion of hydrocarbonsfor the production of gasoline., the process that comprises. subjectinga mixture of cycle condensate and normally gaseoushydrocarbons toconversionV ternp@ratureA ina conversion` zone to effect conversioi/.iinto gasoline constituents, combining the resul-tant products ofconversion. with resi-'ie ual constituents of crude petroleum forreaction in a reaction zone maintained: at` cracking temperature undersuperatrnospheric pressure and wherein separation of vapors from liquidresidue takes place, preventing the accumulation of liquid in saidreaction zone by rapidly withdraw- Y ing the liquid residue, including aportion of the vapors with the vliquid residue Ythus Awithdrawn from thereaction vzonein quantity` sufficient to eifect the autogenous cokingthereof and delivering the mixture to a coking Zone maintained under.reduced pressure wherein coking takes place'wi'thout priming, separatelywithdrawing vapors from said reaction zone, subjecting evolved vaporsfrom the coking zone' and separated vapors fromthe reaction zoneto'fra'ctionation to separate va condensate from heavier and lighterconstituents, cycling said condensate to theV aforesaid,conversionVzone, subjecting said lighter constituents to further fractionation toVseparate normally liquid hydrocarbons from normally gaseous hydrocarbonscomprisingCs and C4 hydrocarbons and cycling such normally gaseoushydrocarbons to said conversion Zone. 2. In the conversion ofVhydrocarbons for the production of gasoline, the process that comprisessubjecting a mixture ofv cycle condensate and'normally gaseoushydrocarbons to conversion temperature in a conversion zone to effectconversion into gasoline constituents, combining the resultant productsof conversion with hydrocarbon oil as hereinafter specied for reactionin a reaction zone maintained at cracking temperature undersuperatmospheric pressure and wherein separation ofvapors from liquidresidue takes place. preventing the` accumulation of liquid in saidreaction zone by rapidly withdrawing the liquid residue, including aportion o the vapors with the liquid residue thus withdrawn from thereaction zone in quantity suicient to eiTect the autogenous cokingthereof and delivering the mixture to a coking zone maintained underreduced pressure wherein coking takes place without priming, separatelywithdrawing vapors from said reaction zione, dephlegmating evolvedvapors from the coking zone and separated vapors iromithe reaction zonewith a crude petroleum residual stock to produce a mixture of residualstock and heavy reflux condensate, utilizing said mixture as thehydrocarbon oil being combined with the products from said conversionzone for reactionV in said reaction zone, subjecting the dephlegmatedvapors to further fractionation to separate reflux condensate from lowerboiling hydrocarbons, cycling said reux condensate to said conversionZone, subjecting the separated lower boiling hydrocarbons to furtherfractionation to separate normally liquid hydrocarbons from normallygaseous hydrocarbons comprisingCg and C4 hydrocarbons and cycling suchnormally gaseous hydrocarbons to said conversion zone. Y Y 3. In theconversion of hydrocarbons for the production of gasoline, the processthat comprises subjectingja mixture of cycle'condensate and normallygaseous hydrocarbons to conversion temperature in a conversion zone toeffect conversion into gasoline constituents, combining the resultantproducts of conversion with hydrocarbon oil as hereinafter specified forreaction in a reactionzone maintained at cracking temperature undersuperatmospheric pressure and from the reaction zone in quantitysuicient to effect the autogenous coking thereof and deliverng themixture to a coking zone maintained under reduced pressure whereincoking takes place without priming, separately withdrawing vapors fromsaid reaction zone, dephlegmating evolved vapors from the coking zone ina dephlegmating zone to form a heavy tarry condensate, passing thedephlegmated vapors to a second dephlegmating zone, directing separatedvapors from said reaction zone to the second dephlegmating zone anddephlegmating the vapors therein with aV petroleum residual stock,

utilizing the resultant mixture of residual stock and heavy reiiuxcondensate as the hydrocarbon oil being combined with the products fromsaid conversion zone for reaction in said reaction zone, subjecting thelatter dephlegmated vapors to further fractionation to separate refluxcondensate from lower boiling hydrocarbons, cycling said refluxcondensate to the aforesaid conversion zone, subjecting said lowerboiling hydrocarbons to further fractionation to separate normallyliquid hydrocarbons from normally gaseous hydrocarbons comprising C3 andC4 hydrocarbons and cycling such normally gaseous hydrocarbons to saidconversion zone.

4. In the conversion of hydrocarbons for the production of gasoline, theprocess that comprises subjecting cycle condensate formed ashereinafterspecified to conversion temperature under superatmosphericpressure in a conversion zone to effect conversion into gasolineconstituents, combining the resultant products of conversion withhydrocarbon oil as hereinafter speciiied for reaction in a reaction zonemaintained at cracking'temperature under superatmospheric pressure andwherein separation of vapors from liquid residue takes place, preventingthe accumulation of liquid in said reaction zone by rapidly withdrawingthe liquid residue, including a portion of the vapors with the liquidresidue thus withdrawn from the reaction zone in quantity sufficient toeffect the autogenous coking thereof and delivering the mixture to acoking zone maintained under reduced pressure wherein coking takes placewithout priming, separately withdrawing vapors from said reaction zone,dephlegmating evolved vapors from the coking zone and separated vaporsfrom the reaction zone with a petroleum residual stock to produce amixture of residual stock and heavy reflux condensate, utilizing saidmixture as the hydrocarbon oil being combined with products from theconversion zone `for `reaction in the reaction zone, subjecting thedephlegmated va'- pors to furtherfractionation to separate refluxcondensate from lower boiling hydrocarbons, directing said refluxcondensate to said conversion Zone, subjecting said lower boilinghydrocarbons to further fractionation to separate normally liquidhydrocarbons from normally gaseous hydrocarbons comprising C3 and C4hydrocarbons, subjecting said normally gaseous hydrocarbons toconversion temperature under superatmospheric pressure to eiectconversion into higher boiling constituents within the gasoline boilingrange and directing the resultant products of the latter conversionV tol`s aid reaction zone.

' CLAUDE W. WATSON.

